In semiconductor industry, integrated circuits continue to use smaller geometries, lower supply voltages, and higher integration. These integrated circuits consequently have higher current densities and increased power dissipation. Accordingly, monitoring of environmental conditions, such as temperatures and power supplies, at the system or circuit board level is now done at the integrated circuit level.
Thermal control circuits used to ensure an integrated circuit does not exceed a factory defined temperature limit have been included in microprocessor integrated circuits. However, having thermal control done by a microprocessor, which may be a central processing unit of a system, adds overhead to processing functionality that may reduce system performance. Accordingly, monitoring may be offloaded to a processor or dedicated monitor. However, conventionally, such offloading involved a three or more additional integrated circuits to provide sufficient additional input/output and busing to support a number of sensors, as well as driver software. More recently, single chip sensor monitors have been developed. However, such single chip sensors heretofore have not provided a substantially complete single chip solution owing to configuration limitations, among other limited features.
Besides monitoring environmental conditions or physical characteristics of a system, it is useful to be able to obtain test data associated with such monitoring. Joint Test Action Group (“JTAG”) functionality is a known way for conducting a boundary scan or otherwise digitally testing an integrated circuit. Additionally, the Institute of Electrical and Electronics Engineers (“IEEE”) has advocated a standard for analog boundary scanning, namely, IEEE 1149.4. Both analog and digital sensors may be useful for monitoring integrated circuit physical characteristics and environmental conditions, whether internal or external to a chassis.
Accordingly, it would be desirable and useful to provide system monitoring in a single integrated circuit that facilitates obtaining data obtained from an analog or digital sensor.